With the help of underground TDS + TGS, the deep pre-concentration of underground 300-13(6)mm raw coal can be achieved. And the separated reject can be used for backfill mining to replace the covered resources such as open mine cornered coal and coal pillars of three-under, thus raising the mine resources recovery rate, prolonging the service time for the mines, and increasing the economic benefits. Meanwhile, underground pre-concentration process can improve the mine raw coal quality, increase the effective capacity of the main shaft. This can help reducing the ground washing system load as well as the mine reject and other solid waste discharge volume to realize green and sustainable development.